Overload circuit-breaker.



H. A EVERETT.

\JVEBLOAD CIRCUIT BREAKER.

APPucATmM HLED FEB. 24, 3915 2 SHEETS-SHEET I Patented May 16, 1916.

lNVENTOR a (M? WITNESSES A'ITORNEY v H. A. EVERETT.

OVERLOAD cmcun BREAKER.

APPLICATION FILED FEB. 24w 1915- Patented May16,1916

2 SHEETS-SHEET 2.

INVENTOR WITNESSES 7 $5 W Bl; 7@ 4 ATTORNEY HENRY A. EVERETT, GFHADDON HEIGHTS, NEW JERSEY.

OVERLOAD CIRCUIT-BREAKER.

Specification of Letters Patent.

Patented May 16, 1916.

I Application filed February 24, 1915. Serial No. 19,203. I

To (lilac/m it may com-cm.

Be it known that I, Hnxnr A. Evi-aui'rr, a

citizen of the United States of America, re-

siding in Haddon Heights, in the county Camden and State of New Jersey, have m vented a certain new and useful improvement in Overload (ircuit-Breakers. of which the following is a true and exact description, reference being had to the accompany ing drawings, which form a part thereof.

My present invention consists in an im proved form of overload circuit breaker adapted, to be connected in circuit w'th an electric motor to interrupt the current flow tl'ierethrough on a predetermined rise and (llll'iltlOIl of that current flow.

The object of my invention the provi sion of an overload circuit breaker of simple construction which is automatic and reliable in operationi is readily portable and adapted to operate in any position in which it may be placed, and is not apt to be injured, or to have its operativencss interfered with by rough usage.

My invention was primarily devised for use in connection with portable electric drills and reainers of the kinds used in ship yards, bridge work and elsewhere, where heavy drilling and reaming operations are carried out under like conditions For such use it has now become desirable to employ quite powerful electric driven portable drills and reamers. In consequence when a drill or reamer bit sticks. as it frequently does when crowded into the work, the powerful motor is apt to twist the bit off, and if the bit' is not broken in this manner, it frequently happensthatthe motor tears loose from the grasp of theoperator. and this, of course. is apt to result in injury to the workman, as well as damage to the tool. If the bit sticks and the motor frame is firmly held by the operator, the motor/is apt to burn out because of the failureof the workman to' open the motor switch quickly enough, especially as these tools are ordinarily operated by unskilled workmen. While there is thus more need for a suitable overload circuit breaker for the protection of an electric motor, used as above specified.'tl1an in the ordinary uses of such motors, the conditions of theuse referred to which make. the circuit breaker especially desirable, make the andready portability coupled with reliability of operation.

The various ""features of novelty which characterize 'my invention are pointed out w' th particularity in the claims annexed to a Q forming a part of this spec fication.

' Fon a better understandingof the invention, 'however. and .of the advantages possessed by it, reference'sliould be had to tll. accompanying drawings and descriptive matter,

in which i have illustrated one form of my invention.

improved safety device comprises a board or block of insulating material A, forming a support on which the rest of the mechanism is mounted. This mechanism comprises a switch mechanism including a stationary contact 13, the base B of which is secured to the support A, and a cooperating contact C. carried by a bell crank or switch'leyer C. The latter is pivoted between the ears D of a bracket D, secured to the support A. To the upper end of the upper arm of the bell crank C is secured a transverse pin C The ends of the pin C are connected by helical springs F, to the ends of 'a pin E which is parallelto the pinch and to the axis of the switch lever C,- and works in slots D formed in the bracket ears D. The slots D extend generally parallel tot-he plane of the support A and asthe pin E is moved from one set of ends'to the other of the. slots D the lines of action of the springs F shift from one side to the other of the fulcrum ,Links G connect the ends of the pin E to the end of the hollow magnetic armature core H of an electric magnet H of the solenoid type mounted on the support A with its axis generally parallel to the direction of the slots D". As shown. the frame or spool of the elcctromagnet H is formed the end remote from theswitch mechanism 7 with a dash-pot cylinderH in which works a dash-pot piston J, connected to the inner end of the armature core H by the nons v 'ply conductor-so and A, which are intacts B and C are separated.

. nagnetic rod J, and the pind The windof t -I electromagnet H comprises a shunt coil 2' and a series coil 1. The armature H is constantly urged into the position "in Which it extends out of the electromagnet and the switch contact C is held against the contact B by resilient loading means, which in the form shown, comprise a pair .jof. helical springs K locatedon opposite sides of the electromagnet and each connected at one end to a corresponding lug-J on the dash-pot piston J. At its opposite ,ends,'each' spring K is connected. to a corresponding bolt L, passing loosely through an aperturein an ear H formed on the end flange of the spool of magnet H adjacent support A and secured to the latter by means of the screws N.

As shown, the two insulation covered supclosed. in a single insulating jacket external to the. safety device, are secured to one end of the support A by binding postsor clamping screws P and P respectively. To the opposite end of the support A binding posts P and P secure the ends of insulation covered conductors O and 0A leading to the "motor R to be protected. External of the safety device the conductors O and 0A are inclosed in a common insulating jacket.

Asillustrated in Fig. 4, the binding post P to which the supply conductor O is secured, is also connected to one terminal of the blow-out-coil M. The other terminal of the latter is connected to the base B of the stationary switch contact B. The bracket D,

and thereby the switch lever C, and contact C, are connected by a conductor 0, to one terminal I of theseries winding I of the electromagnet, and a branch 0 of the conductor O is connected to one terminal 2" of the shunt winding i. A conductor 0 con nects the binding,post 'Pf'to the second terininal i of the shunt windings. As seen in 4, several taps I lead from different portions of the winding I, and the conductor O serves to connect one or another of these taps I to the binding post P. In the conductor 0 leading from the binding post P to the motor R. is connected the operat* ing switch Q for the motor R. Conductor QA' extends between the binding posts P and P and thereby connects conductors 0A and 0A --with the contact" B.

na -muss, with the normal c 'i'ri e nt flow in series through the coil I and motor R,

the tension of the springs K prevent move-' ment of'the' armature H" sufficient to sepa- I of the pinEto the right, as seen in Fig. 2, v

of the plane including the axis of the pins C and the axis of the switch lever C, that the-contact-C is moved out of engagement v VVheri the movement of the armature is sufiicient to separate the contacts, however, the contacts separate with a rapid or snap action. hen the contacts thus separate and the main circuit is current flow between the contacts B and C.

is interrupted. To decnergize the winding and thus permit the return of the apparatus to the condition in which contact 0 engages the contact B, it is necessary to open'the circuit external of the safety device proper. In practice the workman handling the tool of which the motor R is the driving agent, opens the switch Q, to deenergize the coil 2'. This requirement for some active operation on the part of the workman before restarting his motor after the operation of the safety device, is desirable, as it brings to his immediate attention the fact that the tool should be backed olf or adjusted to reduce I theresistance of the work to itsmovement. The daslrpot is an essential characteristic of my device when used with the electr c drills and reamers for which it was especially devised, because with these tools there is a momentary current flow when the operating switch (Q) is closed, necessary to start the motor, which is substantially in excess of the working current which can be safely passed through the motor for any appreciable length of time. The dash-pot operates to prevent the opening of the motor 'circuit on this nion'ientary rush of a current appreciably greater than the current which, if continued for a few seconds would. and should result in the operation of the circuit breaker.

Thestrength of the maximum working current which the safety device will permit to pass may be varied by changing the tap ening or lengthening the winding I, and

.may be adjustedalso'by changing the tension of the springs K;

fInthe practical use of the electric drilling and reaming-tools with which my invention supply conductors, but are plugged into and out of circuit with the fixed conductors at H different points at comparatively frequent intervals as the toolsare shifted. The same;

permanent supply conductors to which any one tool may thus be connected at numerous different points supplies current, in dinary practice, to numerous tools and lights. In consequence, it is essential that the safety device be portable with the motor which it is employed to protect. In practise the portions of the motor supply con- "ductors extending between the motor and the safety device are a few feet in length to permit the safety device to be hung up on a wall or dropped on. a ships deck, bridge girder or other convenient place of support in: proximity to the point at which the tool is used.

It will be apparent to those skilled in the art that my improved safety device while compact, simple in construction and re atively light in weight, is rugged and reliable in operation, and operative in any position which it'may be placed; Ordinarily I attach a chain, 0, as shown, to the support A to permit'the device to be hung up at any convenient place in proximity to the tooi' with which it is employed. but the device will operate equally well when lying fiat or departing from the spirit of my invention.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is-

1. In an overload circuit breaker the combination of a switch including a movable switch opening and closing member, a movable armature,'a mechanical connection between sald armature and member including provlsions for some lost motion and arranged to permit a limited initial movement of the armature 1n\the switchopenmg d1rection without moving said member, but operatingon a further movement of the armature to force said member into the switch open position, yielding means tending to return the armature'to and maintain it in the position in which the switch is closed, a

' winding in series with said switch adapted on a predetermined flow of current therethrough to move the armature .into the switch open position, a winding invshunt to the switch and tending when energized to hold the armaturein the switch open position.

2. In an overload circuit breaker the combination of a switch including a movable switch opening and closing member, a movable armature, a mechanical connection between said armature and member including provisions for some lost motion and arranged to permit a limited initial movement of the armature in the switch opening direction without moving said member but operating on a further movement of the armature to force said member into the switch open posi tion, yielding means tending to return the armature to and maintain it in the position in which the switch is closed, a winding in series with said switch adapted on a predetermined iiow of current therethrough to move the armature into the switch open position, a winding in shunt to the switch and tending when energized to hold the armature in the switch open position, and a dash pot opposing a rapid initial movement but yielding to permit a rapid final movement of said armature in the switch opening direction.

3. In an overload circuit breaker the com- -bination of a quick acting switch mechanism comprising a movable contact, a reciprocating element and a resilient connection between said element and contact put under tension" during and snappingsaid contact into open position at the end of a predetermined movement in one direction of said element. a dash-pot retarding the initial but not the final portion of said pre'determined m nsvement of said element and an eiectromagnet including a winding adapted to be connected in series with said contact in the circuit to be controlled and an armature attached to and actuating said element.

In an overload circuit breaker, the combination of a quick acting switch mechanism comprising a movable contact, a reciprocating elementand a resilient connection between said element and contact put under tension during and snapping said contact into open position at the end of a predetermined movement in one direction of said element, an eiectromagnet comprising an armature connected to said element and effecting the predetermined movement thereof when suficiently energized, and a winding, said winding and contact being adapted to be connected in series in the circuit to be controlled, and the frame of said electromagnet beingi'ormed with an open ended chamber at one end. and a piston connected to said armature and working in said piston chamber and forming with the latter a dash-pot to retard the armature during the initial portion of but not the final portion of said predetermined movement of said element.

5. A portable overload circuit breaker comprising in combination, a support, a stacomprising a frame mounted on said support, an armature connected to, and tend ing to move said element in said guides, and

a winding, said Winding and contacts being adapted to be connected in seriesin. the circuit to be controlled, the frame of said electromagnet being formed with a piston chamher, and a piston connected to said armature and working in said chamber and cooperating with the.la tter to form a dash-pot retarding the initial but not the final portion of the movement of the armature necessary to shift the movable contact from its normal into its open position, and means for imposing an adjustable loading .force on said'armature tending to maintain the latter in the position in Which said movable switch con tact is held in its closed position.-

6: A portable overload circuit breaker comprising in combination, a support, a statlonary contact mounted thereon, a bracket mounted thereon, a bell crank switch lever C ivoted in said bracket and carrvin a.

' one side to the other of the pivotal axis of the lever C as said element is reciprocated, an electromagnet comprising a frame mounted on said support, an armature con: nected to, and tending to move said elementim in said guides, and a winding, said winding and contacts being adapted to be connected in series in the circuit to be-controllecl, the frame of said electromagnet being formed with a piston chamber, a piston connected to said armature and working in said chamber and cooperating with the latter'to form a dash-pot retarding the initial but not the final portion of the movement'of the armature necessary to shift the movable contact from its normal. into its open position, and means for imposing an adjustable loading force on said armature tending to maintain the latter in the position in which said movable switch. contact. is held in its closed position.

' HENRY A. EVERETT.

Witnesses ARNOLD KA'rz,

D. STEWART. 

